Litter boxes are used by pets such as cats for elimination of urine and fecal matter. A litter box contains a layer of pet litter that receives the urine and fecal matter. The pet litter is granular, absorbent and either non-clumping or clumping. A clumping pet litter is a litter product in which the particles facilitate formation of clumps after the urine and fecal matter is deposited in the pet litter. The clumps are typically sifted from the litter box using a litter scoop and then discarded. Non-clumping pet litter is typically better at absorbing urine and thus removing urine odors, but replacing soiled non-clumping pet litter without emptying the entire box of litter can be difficult.
Consumers fill their litter boxes based on volume, so litters should be highly absorbent by volume. However, traditional absorbent litters are bulky and dense, and thus packages of such litters are heavy and difficult to handle.
Existing litters include compositions made from clay minerals, silica gel, and agricultural wastes. Clay minerals are absorptive but also heavy. Silica gel is also absorptive, but the commonly used aggregate shape and size can have poor cat acceptance, which can lead to house soiling and/or a risk of urinary minerals aggregating into stones or crystallizing in a cat. Agricultural wastes are also absorptive, but many are in pellet form and can have poor animal acceptance. Agricultural waste litters, due to their composition, may also serve as food source and thus support growth of odor causing microorganisms in the litter box.
U.S. Pat. No. 5,655,480 to Steckel et al. discloses an animal control litter comprised of a clumping agent, a surfactant, an odor control agent and light weight aggregate expanded to form porous surfaces by subjecting the aggregate to a temperature of 1,800° F. This litter has a density between 5 and 10 lb/ft3. However, the material is less absorptive by volume than clay. Additionally, the expanded perlite aggregate material is fragile and can break down easily. The material may also be “too light” for good cat acceptance.